PERSPECTIVES || JOURNAL OF CREATION 28(2) 2014
Cactus spines,
sharper than you
may think!
Philip Robinson
O
il spills at sea, such as the
Deepwater Horizon oil spill in
the Gulf of Mexico in 2010,1 can be
massively damaging ecological events,
with oil spreading for many thousands
of miles. Biomimetics, the abstraction
of good design from nature,2 is again
providing a useful solution,3 this time
to such disasters. Recently published
cactus-inspired research 4 is aimed
at finding a more effective way of
capturing submerged oil droplets,
which are normally missed in the
cleanup operations, which typically
focus on collecting the oil near the
surface of the water.
A unique system
The new technology builds upon
previous research 5 on the tapered
spines6 of the cactus species, Opuntia
microdasys (fig ure 1), which is
endemic to central and Northern
Mexico, and found in places such as
the arid Chihuahua Desert. It was
discovered that the cactus efficiently
collects water droplets from fog using
a “unique system composed of welldistributed clusters of conical spines
and trichomes on the cactus stem”.7
This occurs because the cactus spines
have an interesting effect on the
water droplets. When micron-sized
spherically shaped water droplets
in the air land on them, the spine’s
conical shape distorts them, forcing
them into a clam-like shape instead.
However, water droplets are inclined
to be spherical, and exert a strong
inward pressure to try and remain so.
In opposition the surface tension wants
the water droplet to be in the clam-like
shape. The battle between these two
forces pushes the droplets from the tip
of the spine 8 toward the cactus plant at
the base of the spine, where the spine’s
surface is less curved and the radius is
larger.9 The cactus’s trichomes at the
base of the spine then immediately
absorb the droplets of water.
Cactus spines have many different
functions, such as offering protection,
shade, and slowing down air currents
arou nd the epider mis to lessen
water loss. The discovery of this
new function, added to the CAM
physiology,10 waxy skin, succulent
tissue, and specialized root system,
are a wonderful example of design
that had to be present and functional
to allow the cactus to live in such harsh
ecosystems as the Chihuahua Desert.
Collecting oil droplets in water
Inspired by the research on the
newly discovered function of the cactus
spines, the design was mimicked and
applied to collecting oil droplets in
water. While oil normally floats on
water, oil spills also produce some
denser micron-sized droplets as the oil
breaks down, which don’t float on the
surface. The current range of cleanup
technologies used on oil spills such as
mechanical skimmers or membrane
filters mainly remove oil from the
surface but miss those denser droplets
that have sunken further down.
To tackle the problem, a team of
scientists in Beijing identified that
“micron-sized oil droplets in water
and micron-sized water droplets in
air are similar, so we can move the
cactus-inspired system underwater”.11
This was done by creating arrays of
conical copper and silicone polymerbased 12 needles to replicate the cactus
spines. “The ability to deposit oil is
based on the intrinsic oleophilicity 13
of these materials under water, and
the canonical structure induces the
directional motion of the collected
oil droplets.” 14 The arrays were then
Figure 1. The cactus Opuntia microdasys.
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JOURNAL OF CREATION 28(2) 2014 || PERSPECTIVES
Thorns and thistles—
degenerative mutations or
divinely designed?
Astute long-time readers of CMI
publications may have noticed something
of an apparent contradiction between the
theme of this perspective article and that
of a previous Creation Magazine article: “A
Thorny Issue”.19 I have put forward in this
article that the cactus spine is not simply
a degenerative mutation but specially
created by God as part of the Curse in
Genesis 3. Scripture suggests that as part
of the Curse genetic changes took place:
a permanent change to the serpent; pain
during child birth; and the introduction
of thorns and thistles.20 There are great
differences in modern names applied to
the all-encompassing “thorns and thistles”
in Genesis 3: thorns, prickles, bristles,
spines, etc. While what may appear to be
a degenerative mutation 21 may explain
one or more of these categories—most
likely thorns and prickles due to their
fairly simple formation, structure, and
position—it surely does not, and cannot,
explain them all due to their individual
complexities, differences, and functions.
While it has been suggested that cactus
spines are mutated leaves, the indication
taken from Scripture and their actual
formation would suggest that they are not.
The cactus researcher Mauseth describes
submerged into a mixture of silicone
oil and water that was blasted with
ultrasonic sound waves to generate
the micron-sized oil droplets. The
team then observed that underwater
oil droplets collect on and flow along
the needles in a similar way that the
water collects on and moves along the
cactus spines. Testing different array
set ups, the team found that an array
with hexagonal grids of the silicone
polymer needles proved to be the most
effective, due to a higher density of
needles, separating up to 99% of the oil
from the water. This new technology,
if it can replicate the same results
in a genuine oil spill, could prove to
be a very effective tool in cleanup
operations.
10
the difference in the formation of cactus
spines and the cactus leaf,
“Evolution appears to have been
more complex than would be expected:
mature cactus spines do not contain
any of the cells or tissues characteristic
of leaves, and conversely leaves lack all
features characteristic of spines. The two
organs have little in common other than
developing from leaf primordia. Spines
consist of just a core of fibers surrounded
by sclereid-like epidermis cells. They have
no stomata, no guard cells, no mesophyll
parenchyma, no xylem, no phloem. When
mature, all cells in a spine are dead, and
even when the spine is still growing it
has living cells only at its base. Cactus
leaves on the other hand —even the
microscopic leaves of Cactoideae—have
parenchymatous epidermis cells, guard
cells, spongy mesophyll, chlorenchyma,
xylem, and phloem. So the evolutionary
conversion of cactus leaves into spines did
not involve a mere reduction of the lamina
and then further reduction of midrib and
petiole, it instead involved the suppression
of all leaf-cell-type genes and activation of
genes that control formation of fibers, the
deposition and lignification of secondary
walls, and then programmed cell death.
These fiber morphogenesis genes are not
activated in any cactus leaf (none at all has
fibers), but they are activated of course in
the development of wood. It would appear
that after an axillary bud apical meristem
Origin of the cactus spine
This incredible feature of the cactus
spine, inspiring new technology, was
given the usual evolution lip service,
with no explanation offered as to how
it or the laws of physics that it utilizes
may have arisen.
Very few cactus fossil specimens
have ever been found,15 meaning
that, for the evolutionist, “the timing
of cactus origins and diversification
has remained enigmatic.” 16 From a
biblical perspective we know both
the origin of the cactus spine and
that of the fossils. Cactus spines
are a reminder of the entrance of
sin into the perfect world that God
had created for man, and the subsequent Curse on creation detailed in
initiates spine primordia, most leaf genes
remain suppressed and instead wood fiber
genes are activated. This does not involve
all wood genes because vessels are never
produced in the spines, just wood fibers.”22
W hil e M ause t h has in c o r re c tl y
attributed the formation of the cactus
spine to evolution, what should be
abundantly clear from his description
is that the attribution of a naturalistic
degenerative mutation for the formation
of a cactus spine cannot be correct
either. The cactus spine would not only
require the loss of cells, vascular tissue,
etc., found in leaves, but would require
specific genetic information to develop.
The description above would be true for
the basic plan of each cactus spine, but
even cactus spines are wide ranging in
their final forms, possibly requiring further
specific information. As it requires the
activation of specific genes at the correct
time for the spine to form, this would
indicate that it was indeed designed,
possibly involving the activation of latent
genetic information used in the formation
of cactus spines being unmasked at the
Fall. This would fit well with God, who is
purposeful in everything that he does,23
even when implementing the Curse,
making the cactus spine’s numerous
obvious functions and its newly discovered
function a design feature attributed to
God’s intricacy and creativeness.
Genesis 3.17 The cactus fossil specimens
formed from cactuses buried during
Noah’s Flood, the Flood judging
mankind’s wickedness, and being
referred to by Jesus as both a real
historical event and an example of his
coming judgment.18 Yet even in such
a spiny reminder of our fall we see
the evidence of God’s great design,
purpose, and providence.
Conclusion
This new technology is only a copy
of the real thing. The design feature
and the laws of physics that it utilizes
are a clear and powerful demonstration
of the mind behind them, revealing the
Creator God.
PERSPECTIVES || JOURNAL OF CREATION 28(2) 2014
References
1. A large accidental marine oil spill with a sea-floor
oil gusher flowing for 87 days and discharging an
estimated 760 million litres (200 million US gallons)
of crude oil. Over 8,000 animals were reported dead
due to the effects of the oil spill in the first 6 months.
2. Reading University, UK, Biomimetics department,
home webpage definition of biomimetics; www.
reading.ac.uk/biomimetics/about.htm, accessed 20
January 2014.
3. See creation.com/design-features-questions-andanswers for more examples.
4. Li, K. et al., Structured cone arrays for continuous and effective collection of micron-sized oil
droplets from water, Nat. Commun. 4:2276, 2013;
doi: 10.1038/ncomms3276.
5. Ju, J. et al., A multi-structural and multi-functional
integrated fog collection system in cactus, Nat.
Commun. 3:1247, 2012; doi: 10.1038/ncomms2253.
6. Technically called glochids, which are very small
barbed spines that are deciduous.
7. Ju et al., ref. 5, p. 1.
8. Or the barb that it lands on.
9. The gradient of surface-free energy and gradient
of Laplace pressure are believed to be the pri-mary
driving forces behind these phenomena. The water
droplet always moves towards the base of the spine
regardless of the angle of the spine.
10. Batten, D., C4 photosynthesis—evolution or design?
J. Creation 16(2):13–15, 2002; endnote 2; creation.com/
c4-photosynthesisevolution-or-design.
11. Li et al., ref. 4, p. 2.
12. T h e s i l i c o n - b a s e d o r g a n i c p o l y m e r w a s
Polydimethylsiloxane (PDMS).
13. Meaning that the materials have a strong affinity for
oils rather than water.
14. Li, ref. et al., 4, p. 5.
15. Chaney, R., A fossil cactus from the Eocene of Utah,
American J. Botany 31(8):507–528, 1944.
16. Arakaki, M. et al., Contemporaneous and recent
radiations of the world’s major succulent plant
lineages, PNAS 108(20):8379–8384, 2011.
17. “Because you listened to your wife and ate from
the tree about which I commanded you, ‘You must
not eat of it’, cursed is the ground because of you;
through painful toil you will eat of it all the days
of your life. It will produce thorns and thistles for
you, and you will eat the plants of the field. By the
sweat of your brow you will eat your food until you
return to the ground, since from it you were taken;
for dust you are and to dust you will return” (Genesis
3:17–19).
18. Matthew 24:37–44.
19. Catchpoole, D., A thorny issue, Creation 34(3):52–55, July
2012; creation.com/a-thorny-issue.
20. Batten et al., The Creation Answers Book, chapter
6, How did bad things come about? creation.com/
images/pdfs/cabook/chapter6.pdf
21. While these may appear to be a degenerative
mutation due to their relative simplicity in formation
compared to the cactus spines, it does not mean
that they are, and it is highly likely that they were
implemented by God as part of the Genesis 3 Curse.
22. Mauseth, J.D., Cactus Spines—The evolutionary
c o n ve r s io n of l e a ve s t o s p i n e s i n c a c t i ,
tinyurl.com/cactispine a c c e s s e d 20 Ja nu a r y
2014. James D. Mauseth is a Professor in the
Depar tment of Integrative Biology, College
of Natural Sciences, The University of Texas
at Austin.
23. Proverbs 16:4.
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